1. Field of the Invention
The invention relates to a manual piston pump having a blockable dispensing head for dispensing fluid substances, having a cylinder, an inner locking sleeve forming a cylindrical passage for a hollow piston rod to pass through, one end of this extending into a pump chamber of the cylinder and the other end carrying the dispensing head, which is provided with an outer shaft section, a spring which presses the piston rod outwards in relation to the cylinder, into a rest position, and in opposition to the spring force whereof the piston rod may be lowered by pressing on the dispensing head in order to dispense substance, and having a means for blocking the dispensing head, this means including at least one projection which can be placed in engagement with a recess.
2. State of the Art
DE 33 16 308 A1 discloses a manual pump which has a dispensing head mounted on the shaft of the pump itself. In the normal rest condition, this shaft projects beyond the exterior of a hollow main part forming the base body of the pump. The lower end of a hollow movable shaft extends inside the cavity of the main part and is pressed outwards by a spring acting on its lower end. Furthermore, a locking sleeve is fixedly connected to the hollow main part. The pump has one or more cams or small teeth or projections, as a result of which the dispensing head may be locked to the locking sleeve. Moreover, the pump has one or more sealing inserts which close off in relation to the outside atmosphere when the dispensing head is locked on the base body of the pump.
The advantage of a lockable dispensing head is linked to the disadvantage that, when the dispensing head is pressed down, it is frequently skewed. When the dispensing head is skewed, the piston strokes are not performed in their entirety, with the result that these strokes are performed multiple times, which means that undesirable excessive quantities are then supplied. Furthermore, there is increased wear.
The object of the invention is therefore to provide a manual piston pump having a cylinder, an inner locking sleeve forming a cylindrical passage for a hollow piston rod to pass through, one end of this extending into a pump chamber of the cylinder and the other end carrying the dispensing head, which is provided with an outer shaft section, a spring which presses the piston rod outwards in relation to the cylinder, into a rest position, and in opposition to the spring force whereof the piston rod may be lowered by pressing on the dispensing head in order to dispense substance, and having a means for blocking the dispensing head, this means including at least one projection which can be placed in engagement with a recess, which is equipped with a locking sleeve and at the same time operates reliably and with low wear.